Aluminum alloys



UNITED STATES PA'TENT OFFICE ALUMINUM ALLOYS Robert T. Wood, Cleveland,Ohio, assignor to Aluminum Company of America, Pittsburgh, Pa., acorporation of Pennsylvania No Drawing. Original application September21, 1932, Serial No. 634,155. Divided and this application November 30,1932. Serial No. 645,112

1 Claim. (Cl. 75-1) This invention relates to aluminum base alloys thefree passage of the metal through the apercontaining magnesium. Theinvention has for tures. Regardless of the cause of this low fluiditsobject the improvement of alloys of this class ity, I have discoveredthat the addition to the by the addition thereto of about 0.05 to 2.0per alloy of relatively small amounts of calcium, in

5 cent by weight of calcium. The invention is the preferred rangebetween 0.05 to 0.5 per cent, 60

particularly concerned with the specific alloys improves the castingcharacteristics to a very hereinafter described. considerable extent andsimultaneously effects a The claim of this application covers certainreduction of the scum or dross collecting at or matter divided from mycopending application near the surface. In the casting of articles inSerial No. 634,155 which is, in part, a continuasand molds, I prefer toadd calcium in amounts 5 tion of my copending application Serial No.less than about 0.5 per cent except in instances 595,231. Inventionsdsclosed but not claimed where some reduction of tensile strength orherein are claimed in my copending applications other mechanical ortensile property is immate- Serial Nos. 595,231, filed February 25,1932, 645,- rial. In amounts of more than 0.5 per cent the 108 to645,111 inclusive, and 645,113 to 645,125 calcium addition produces theadvantages enuinclusive, all filed November 30, 1932. merated herein buthas a tendency to lower some Considerable difiiculty has heretofore beenenof the physical properties of the alloys. This countered in attemptsto commercially produce effect is not harmful when calcium is present incastings of aluminum base alloys containing amounts of about 0.5 percent or less, but when 20 substantial amounts of magnesium. Thisdiflihigh strength is not a desideratum the calcium culty is encounteredboth in the making of sand may be used in amounts up to about 2.0 percent. castings and permanent mold or chill-mold cast- In intricatepermanent mold castings, where ings, although the nature of thedifliculty difiers casting troubles are very serious if no calciumsomewhat in each case. In the case of sand be added, the improvedphysical properties ob- 25 castings there occurs a reaction between thetained coincident with the production of good molten aluminum base alloycontaining magnecastings more than offset the diminution in slum and theordinary sand-mold materials, or properties which might otherwise resultfrom vapors generated therefrom. There is also a rethe use of thecalcium. action with the atmosphere. In addition, the I have alsodiscovered that when calcium is 30 magnesium-containing aluminum basealloy does added to aluminum base alloys containing magnot flow freelythrough narrow mold sections at nesium, the amount of gas evolved duringsolidordinary pouring temperatures and, if the pouriflcation of thealloys is considerably reduced. ing temperature be raised, thesolidifled alloy is When from about 0.05 per cent to 2.0 per centunsound. If the aluminum base alloy containby weight of calcium is addedto the alloys, the

35 ing magnesium be cast in a chill-mold the reacamount of gas evolvedbecomes less marked with tion effect is minimized to some extent, butthe increasing calcium content and the reduction troubles arising fromcold-shuts and mis-runs of gas evolution may be so marked that themolare accentuated because of the more rapid chillten metal cools tothes'olidification temperature ing of the molten metal. Theconsiderations with a smooth mirror-like surface. I prefer to 40 applyto the aluminum base alloys specifically restrict the amount of calciumadded to 2.0 disclosed herein and particularly to such alloys. per centor less since above this amount the I have discovered that when calciumis added physical properties of the alloys may be too seto aluminum basealloys of the type and comriously aifected. If the best physicalproperties position herein described, these difiicultiesare, are-desiredwith an improved, although not 45 to a considerable extent, eliminated.The calcomplete, degree of gas prevention, I keep the cium should bepresent in amounts ranging from calcium content of the alloys between0.05 per 0.05 per cent to 2.0 per cent by weight subject cent and about0.5 per cent. to specific considerations as hereinafter disclosed. Inthe application of the principles of my in- In the melting of aluminumalloys of the comvention I have determined that certain alumi- .50positions herein described, a viscousscum often num base alloyscontaining magnesium are parforms at the surface of the molten metal.Failticularly benefited thereby. For example, a very ure of the moltenmetal to run properly through useful aluminum base alloy is onecontaining narrow mold apertures is caused, in part, by about 2.0 to 9.0per cent of magnesium and 0.05 shreds or particlesof this scum beingsuspended per cent to 2.0 per cent of calcium, as is also 55 in themolten metal and ofiering a resistance to aluminum base alloy containingabout 2.0 to

15.0 per cent of magnesium, 0.1 to 3.5 per cent of cobalt, and 0.05 to2.0 per cent of calcium to which other elements such as copper,antimony, bismuth, nickel, manganese, and other well known alloyingelements may be added to produce particular properties therein.

Likewise is the addition of 0.05 to 2.0 per cent of calcium beneficialto those aluminum base alloys which contain about 2.0 to 15.0 per centof magnesium and 0.05 to 0.4 per cent of at least one of the class ofmetals here defined as antimony and bismuth, such alloys being veryuseful where use at high temperatures is contemplated. Calcium maylikewise be added to improve such alloys when they contain,-in additionto magnesium and antimony and/or bismuth, one or more of such alloyingelements as cobalt, copper, nickel, manganese, zinc, etc. which may beadded to modify or produce a specific property in the alloy.

The addition of 0.05 to 2.0 per cent of calcium is very beneficial inthe case of a series of aluminum base alloys which contain as majoralloying elements about 2.0 to 10.0 per cent of mag- -nesium and about0.2 005.0 per cent of nickel.

For instance, an aluminum base alloy containing 3.0 to 7.5 per cent ofmagnesium and 0.2 to 2.0 per cent of nickel is improved by the additionof 0.05 to 2.0 per cent of calcium as is,

invention is one containing 3.0 to 8.0 per cent of magnesium, 0.5 to 4.0per cent of nickel, 0.5 to 4.0 per cent of manganese, and 0.05 to 2.0per cent of calcium, which alloy may also be improved, particularly forapplication at high temperatures, by the addition of 0.05 to 0.4 percent of at least one of the class of elements composed of antimony andbismuth.

The principles of my invention find particular application in the caseof aluminum base alloys containing magnesium, nickel, and chromium, andaluminum base alloys containing magnesium, nickel, and copper, as wellas those alloys containing magnesium, nickel, and cobalt. Examples maybe given of aluminum base alloys containing 2.6 to 10.0 per cent ofmagnesium, 0.2 to 5.0 per cent of 'nickel, 0.5 to 3.5 per cent ofchromium, and 0.05 to 2.0 per cent of calcium. An aluminum base alloycontaining 3.0 to 8.0 per cent of magnesium, 0.5 to 3.5 per cent ofnickel,

0.5 to 3.5 per cent of chromium, and 0.05 to 2.0

per cent of calcium has excellent casting properties and the hightemperature properties of this alloy can be favorably afiected .by theaddition of 0.05 to 0.4 per cent of at least one of a class 0! elementscomposed of bismuth and antimony.

Examples may be given of aluminum base alloy containing 2.0 to 10.0 percent of magnesium, 0.2 to 5.0 per cent of nickel, 1.0 to 6.0 per cent ofcopper, and 0.05 to 2.0 per cent of calcium. An excellent alloy of thistype is one containing 3.0 to 8.0 per cent of magnesium, 0.5 to 5.0 percent of nickel, 1.0 to 6.0 per cent of copper, and 0.05 to 2.0 per centof calcium with or without 0.05 to 0.4 per cent of at least one of theclass of elements composed of antimony and bismuth and with or withoutthe further addition of 0.5 to 3.5 per cent of at least one of a classof elements composed of cobalt and chromium, and with or without thefurther addition of 0.1 to 1.0 per cent of at least one of a class ofelements composed of tungsten, vanadium, molybdenum, titanium, andzirconium.

Other excellent alloys are those aluminum base alloys containing about2.0 to 10.0 per cent magnesium, 0.2 to 5.0 per cent nickel, 0.1 to 3.5per cent cobalt, and 0.05 to 2.0 per cent of calcium. A particularexample of this class of alloys, which may also contain withconsiderable advantage 0.05 to 0.4 per cent of a class of elementscomposed of antimony and bismuth, is the aluminum base alloy containing3.0 to 8.0 per cent magnesium, 0.5 to 4.0 per cent nickel, 0.1 to 3.0per cent cobalt, and 0.05 to 2.0 per cent calcium.

Among other magnesium-containing aluminum base alloys which I have foundto be particularly benefited by the presence of calcium are numbered thealuminum base alloys contain- 'ing 3.0 to 8.0 per cent oi magnesium, 1.0to 6.0

per cent of copper, 0.5 'to 3.5 per cent of chromium, and 0.05 to 2.0per cent of calcium, with or without the addition of 0.05 to 0.4 percent of at least one of a class of metals composed of antimony andbismuth and with or without the addition of other alloying elements.

The alloys herein described may be produced by the usual methods ofalloying metals. The calcium is preferably added to the molten alloy bythrusting the calcium beneath the surface with tongs or other suitableinstrument. The aluminum used in preparing the alloys may be pure or itmay contain the impurities found in commercial grades of this metal.Ordinarily a good commercial grade of virgin aluminum will giveexcellent results and is preferable.

Having thus explained and described my invention, I claim:

A metallic alloy consisting of 2.0 to 15.0 per cent by weight ofmagnesium, 0.05 to 0.4 per cent by weight of a class of elementscomposed of antimony and bismuth, and 0.05 to 2.0 per cent by weight ofcalcium, the balance being aluminum.

ROBERT T. WOOD.

